CoinGecko: 18,000+ coins, no key required to start reading

What it covers

CoinGecko tracks price, market cap, trading volume, and metadata for coins and tokens across a long list of exchanges. GET /coins/list, called live with no key, returned 18,414 tracked coins; a separate call to /coins/markets reported 15,980 of those currently carrying live market data, and /exchanges/list listed 1,488 exchanges. The gap between the two coin counts is real: the fuller list includes coins CoinGecko still tracks metadata for but that aren't actively trading anywhere right now.

Beyond simple price lookups, the same API surfaces exchange tickers, historical OHLC and market-chart data back to a coin's listing date, and an onchain/DEX side covering pools and tokens across 200+ networks, per CoinGecko's own docs; that same onchain data is what powers GeckoTerminal. It all comes back as JSON from one API family, whether you're asking about a centralized exchange or a decentralized pool.

Auth and pricing, as they actually work today

Three tiers exist, not two. There's a fully keyless path (no account, no key, works today, is what GET /simple/price and GET /coins/markets both did for us over plain HTTPS), a free Demo API key you get by signing up for a dashboard account, and paid plans above that. CoinGecko's own docs name the paid tiers as Basic, Analyst, Lite, Pro, Pro+, and Enterprise, but we couldn't pull specific prices or monthly-credit figures for any of them: the public pricing page sits behind a Cloudflare bot challenge that blocked our fetch outright, so we're not repeating a number we couldn't verify.

What is documented plainly: every successful (HTTP 200) request against a keyed plan burns one credit from that month's quota, and failed requests don't spend a credit but still count against the per-minute rate limit. That accounting detail matters more than the sticker price if you're budgeting a bot around a monthly cap.

Rate limits and CORS, the fine print that actually bit us

CoinGecko's docs describe the keyless tier's limit as IP-based and shared across everyone hitting the API from that address, rather than a fixed per-key number. We found out what that means in practice: after a handful of successful keyless calls this session, our very next request came back HTTP 429 with retry-after: 54 and a body pointing at the pricing page. That's the shared-IP throttle the docs warn about, catching us mid-session, not a hypothetical. A registered Demo API key gets a flat, documented 100 calls/min instead of sharing a pool with strangers.

CORS is switched on for browser use: re-running both GET /simple/price and GET /coins/markets with an Origin: https://greatapis.com header returned access-control-allow-origin: * on each, plus a Vary: Origin header showing the server actually evaluates the cross-origin request rather than echoing a static wildcard.

Why it's worth a look

The Demo API's OpenAPI spec, published on GitHub at coingecko/coingecko-api-oas and already checked into this catalogue, resolves to 61 real operations, matching what a live fetch of the same file returns today. Two official SDKs (TypeScript and Python, both under CoinGecko's own GitHub org) wrap that spec, and status.coingecko.com tracks uptime and incidents on infrastructure separate from the docs site.

The newest addition is a free, keyless MCP server at mcp.api.coingecko.com/mcp, documented alongside a paid version with higher limits and a locally-run npm package. For anyone wiring an AI agent up to live market data, that's a second free on-ramp next to the REST API.